This application discloses and claims an improvement on the invention of my prior U.S. Pat. No. 3,968,857, the entire disclosure of which is incorporated herein by reference.
The owners of storage tanks, smoke stacks, television towers, tall buildings and other storage bins and silos subject themselves to possible liability resulting from unauthorized use by children of the permanent ladders secured thereto. Where a child wanders onto the property on which a storage tank or silo is located, and is injured while climbing the ladder, the owner of the property may be liable. Therefore there is a need for some type of safety shield for preventing unauthorized use of the ladder.
My prior patent provided such a shield, which has achieved considerable commercial success and generally functions quite well. However, experience has indicated a couple of aspects of the apparatus which could benefit from further improvement. First, the shield has been constructed to receive an eye-bolt through which a padlock or the like is passed to lock the shield in place preventing access to the ladder. In order to permit various padlock designs to be used, it has been necessary to make the eye-bolt opening large enough to receive the largest of the possible padlocks. When smaller padlocks are used, this results in some continuing freedom of movement of the shield. Since the shield is mounted outdoors at an elevation, the wind continually moves the shield, resulting in excessive wear and possible premature failure.
Second, when the shield is mounted on most ladders, it does an excellent job of preventing unauthorized use of the ladder, because the shield includes rearwardly extending side shields to prevent access to the backside of the ladder rungs. However, other ladders are spaced away from their supporting structures an unusually large distance (e.g. more than the seven inches (18 cm) required by OSHA) and thereby provide a "backdoor" access to the ladder, permitting intruders to circumvent the shield.
Thus, there is a continuing need in the art for an improved ladder shield to prevent excess play of the shield, and to prevent "backdoor" access.